Background: Nephrectomy often is required during en bloc resection of a retroperitoneal sarcoma (RPS) to achieve an R0 or R1 resection. The impact of nephrectomy on postoperative renal function in this patient population, who also may benefit from subsequent nephrotoxic systemic therapy, is not well described. Methods: The United States Sarcoma Collaborative (USSC) database was queried for patients undergoing RPS resection between 2000 and 2016. Patients with missing pre- or postoperative measures of renal function were excluded. A matched cohort was created using coarsened exact matching. Weighted logistic regression was used to control further for differences between the nephrectomy and non-nephrectomy cohorts. The primary outcomes were postoperative acute kidney injury (AKI), acute renal failure (ARF), and dialysis. Results: The initial cohort consisted of 858 patients, 3 (0.3%) of whom required postoperative dialysis. The matched cohort consisted of 411 patients, 108 (26%) of whom underwent nephrectomy. The patients who underwent nephrectomy had higher rates of postoperative AKI (14.8% vs 4.3%; p < 0.01) and ARF (4.6% vs 1.3%; p = 0.04), but no patients required dialysis postoperatively. Logistic regression modeling showed that the risk of AKI (odds ratio [OR], 5.16; p < 0.01) and ARF (OR 5.04; p < 0.01) after nephrectomy persisted despite controlling for age and preoperative renal function. Conclusions: Nephrectomy is associated with an increased risk of postoperative AKI and ARF after RPS resection. This study was unable to statistically assess the impact of nephrectomy on postoperative dialysis, but the risk of postoperative dialysis is 0.5% or less regardless of nephrectomy status.